This invention relates to methods and apparatus for connecting the corresponding wires of associated pairs of wires to each other in separate electrical connections and for forming tap connections to pairs of wires. The invention is herein disclosed as an embodiment which is primarily intended for splicing the ends of two multi-conductor cables and for forming tap connections to the conductors in a multi-conductor cable. However, the principles of the invention can be employed under other circumstances which will be apparent from the following description.
Communications cables of the type used to carry telephone signals between different locations commonly comprise a plurality of pairs of insulated wires which are contained within an insulating sheath. These communication cables are made in several sizes, the largest of which contains 4200 pairs of AWB 22 wires. A commonly used size contains 3000 pairs of wires and has a diameter of about 3 inches although cables containing fewer than 3000 pairs are also widely used.
It will be apparent that communication cables can be manufactured only in limited lengths and that when the telephone line between two locations is initially installed, it is necessary to splice many sections of cable to each other at regular intervals. For example, a 3,000 pair cable is usually manufactured in 800 foot lengths which means that when a cable of this size is installed between two locations, a cable splice must be made every 800 feet and each splice requires 6,000 individual electrical connections to connect the individual wires in the end of one cable section to the wires in the adjoining cable section.
The first method used for joining wires in a cable splice was to simply twist the wires together and position a fabric insulating sleeve over the twisted splice connection between the two wires. In recent years, the twisting method has been largely replaced by electrical connectors of several different types. Simple pig-tail connecting devices which receive the ends of the two wires (in one end of the connector) hav been widely used as have crimped connecting devices which receive one wire at each end thereof. U.S. Pat. No. 3,328,872 shows the latter type of crimp-type connecting device and also discloses a simple hand tool for crimping the connector onto the wires. Module type connecting devices have also been employed to some extent. These devices comprise plastic modules which contain a plurality of meallic terminals, each of which receives two wires as shown in U.S. Pat. No. 3,496,522. The tooling for crimping connecting devices in communications cables is becoming highly developed and as a result, a substantial improvement in productivity has been achieved as a result of the use of connectors in cable splicing operations.
The production rates achieved by a craftsman splicing a telephone cable still leave much to be desired, notwithstanding the improvement of recent years. Production rates of 200 to 250 pairs of wires per hour are now being achieved but even at these rates, twelve or more hours are required to splice two sections of a 3,000 pair cable to each other. It will thus be apparent that there continues to be a need for further improvements in this art, particularly improvements which will increase the production rate of the technician engaged in a splicing operation.
The instant invention is specifically directed to an improved method and apparatus for cable splicing and particularly to the achievement of a substantial increase in splicing rates. In general, the method of the invention comprises feeding a strip of connectors from a reel along a path extending through an operating zone and linearly towards the cables being spliced. The wires in the cables are conveniently located on each side of the operating zone so that a wire pair can be moved into the zone by the operator with a minimum of effort. The wires are trimmed and inserted into a connecting device at an insertion station. The connecting device with the wire attached thereto is then delivered to the vicinity of the cable during a subsequent operating cycle.
It is accorcingly an object of the invention to provide an improved method and apparatus for connecting wires to each other. A further object is to provide an improved method and apparatus for splicing the ends of multi-conductor cables to each other. A further object is to provide a cable splicing apparatus which can be operated at a high production rate with a minimum of operator fatigue. A further object is to provide an improved pneumatically actuating cable splicing apparatus. A further object is to provide a compact and rugged power actuated apparatus for splicing electrical cables which can be used efficiently under unfavorable circumstances, such as in a manhole. A further object is to provide an apparatus which can be used for cable splicing operations and which can also be used to form tap connections to cables.